| Group | 13 | Melting point | 660.323 oC, 1220.581 oF, 933.473 K |
| Period | 3 | Boiling point | 2519 oC, 4566.2 oF, 2792.15 K |
| Block | p | Density (kg m-3) | 2698 |
| Atomic number | 13 | Relative atomic mass | 26.982 |
| State at room temperature | Solid | Key isotopes | 27Al |
| Electron configuration | [Ne] 3s23p1 | CAS number | 7429-90-5 |
| ChemSpider ID | 4514248 | ChemSpider is a free chemical structure database | |
Image explanation
Aircraft fuselage and aluminium foil - two of the many and varied uses of this element.
Appearance
The most abundant of metals. A lot of energy is needed to extract it from its ores : however, this is worthwhile because it does not rust and is fairly easy to recycle. It is lightweight but tough, and is widely used for window frames, aircraft parts, engines, kegs, cooking oil, drinks cans, etc. Only a small amount of what we take in with our food is absorbed by our bodies. Foods with above average amounts of aluminium are tea, processed cheese, lentils and sponge cakes (where it comes from the rising agent). Cooking in aluminium pans does not greatly increase the amount in our diet except when cooking acid foods such as rhubarb. Some indigestion tablets are pure aluminium hydroxide !
Uses
Aluminium is used in an enormous variety of products, due to its particular properties. It has low density, is non-toxic, has a high thermal conductivity, has excellent corrosion resistance, and can be easily cast, machined and formed. It is also non-magnetic and non-sparking. It is the second most malleable metal and the sixth most ductile. It is therefore extensively used for kitchen utensils, outside building decoration, and in any area where a strong, light, easily constructed material is needed. The electrical conductivity of aluminium is about 60% that of copper per unit area of cross-section, but it is nevertheless used in electrical transmission lines because of its low density. Alloys of aluminium with copper, manganese, magnesium and silicon are of vital importance in the construction of aeroplanes and rockets. Aluminium, when evaporated in a vacuum, forms a highly reflective coating for both light and heat which does not deteriorate as does a silver coating. These aluminium coatings are used for telescope mirrors, in decorative paper, packages and toys, and have many other uses. It is lightweight but tough, and is therefore widely used for window frames, aircraft parts, engines, kegs, cooking oil, drinks cans, etc.
Biological role
Aluminium has no known biological role. It can be accumulated in the body from daily intake, and at one time was suggested as a potential causative factor in Alzheimer’s disease (senile dementia), although some studies have disproved this theory. Only a small amount of what we take in with our food is absorbed by our bodies. Foods with above average amounts of aluminium are tea, processed cheese, lentils and sponge cakes (where it comes from the rising agent). Cooking in aluminium pans does not greatly increase the amount in our diet except when cooking acid foods such as rhubarb. Some indigestion tablets are pure aluminium hydroxide.
Natural abundance
Aluminium is not found uncombined in nature, but is the most abundant metal in the Earth’s crust (8.1%) in the form of minerals such as bauxite and cryolite. Most commercially produced aluminium is obtained by the Bayer process of refining bauxite. In this process the bauxite is refined to pure aluminium oxide, which is mixed with cryolite and then electrolytically reduced to pure aluminium. A lot of energy is needed to extract it from its ores: however, this is worthwhile because it does not rust and is fairly easy to recycle.
| Atomic radius, non-bonded (Å) | 1.840 | Covalent radius (Å) | 1.24 |
| Electron affinity (kJ mol-1) | 41.747 |
Electronegativity (Pauling scale) |
1.610 |
|
Ionisation energies (kJ mol-1) |
1st
577.539
2nd
1816.677
3rd
2744.779
4th
11577.459
5th
14841.845
6th
18379.477
7th
23326.276
8th
27465.493
|
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| Common oxidation states | 3 | ||||
| Isotopes | Isotope | Atomic mass | Natural abundance (%) | Half life | Mode of decay |
| 27Al | 26.982 | 100 | - | - | |
|
Molar heat capacity (J mol-1 K-1) |
24.2 | Young's modulus (GPa) | Unknown | |||||||||||
| Shear modulus (GPa) | Unknown | Bulk modulus (GPa) | Unknown | |||||||||||
| Vapour pressure | ||||||||||||||
| Temperature (K) |
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| Pressure (Pa) |
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Images: Visual Elements © Murray Robertson 2011
Mining and Sourcing data: British Geological Survey – natural environment research council.
Text: John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.
Mining and Sourcing data: British Geological Survey – natural environment research council.
Text: John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.
